She wants to become a singer so much in the anime. She also loves Eichi so much that when she goes to America and finds out that Eichi has died, she breaks down. She breaks down and agrees to do the surgery that will remove her of her singing abilities. In the manga, it is even more harsh. She knows Eichi is dead and is using it as a fake reason to want to sing so badly.

In the manga, Eichi dies on the plane that goes to the news and Mitsuki already knows. In the anime, Eichi dies without Mitsuki knowing until she finds out herself by going to America. Which one is harsher do you think?

Aoi Koga, Takuto Kira, and Keiichi Wakaoji are all part of the band Route L.

Nachi and Madoka fall in love, though Gut-chan is jealous of him. When Madoka finds he has an old photo of her with her unattractive childhood fiancé, Soichiro Shido (紫堂 総一郎, Shidō Sōichirō?), she assumes Nachi is Soichiro's friend, pretending to love her to get revenge for Soichiro for rejecting him hurtfully. Madoka then apologizes to Soichiro's mother and asks to break off the engagement because she loves Nachi, only to discover Soichiro is Nachi, after having plastic surgery to become an idol in hopes of making her love him. In the end, they remain engaged.

He also falls in love with Mitsuki. In the manga, he realizes he was in love when he was alive as well. When he was alive in the manga AND anime, he was part of Route L.

Jonathan has a large role in the manga. He reveals to Mitsuki that the shinigami knew that Eichi had died, and later becomes a fanatic who tries to harm Fullmoon and her friends. Near the end of the manga, he reveals his true form: Sheldan, the head of the pediactrics ward, and attempts to take Mitsuki's life before being stopped by Takuto, Meroko, and Izumi. He was the second shinigami, after Mystere, and appears to show her great affection. In the final chapter, he uses up all his powers with Mystere to heal Takuto's throat and give him his voice back, and disappears along with Mystere.
In the anime, Jonathan's role is minor, limited to following Izumi around, to Izumi's annoyance.

She was the first human soul to descend to the Underworld, and is known as the Death Master and was crowned queen of the Underworld. She is also called Mystere (ミスティア, Misutia?). After discovering she could take the souls of humans, she encountered a dying young girl who asked her if she was a shinigami, and convinced herself that she is one. She is a very fragile and sentimental person and apparently is one of the most powerful of the shinigami. When Meroko enters her room to erase Mitsuki's name from the rolls of the dead, Mystere gives her the keys to free Takuto, and later she listens with a smile to Mitsuki's final performance as Fullmoon. At the end of the manga, when Mystere and Sheldon disappear after using up their power healing Takuto's throat, they appear to show great affection for each other, and Mystere says that unlike the last time she died, she has no regrets about it.